I'm pretty sure the State of Texas sued, or threatened to sue, Amazon to collect back sales tax the State claimed was due. The resulting deal was Texas would waive the back sales tax, but Amazon agreed to collect sales tax from Texas customer begining 7/1/12.
On the plus side, Amazon UK doesn't charge any tax. Shipping yes, but no tax. I just pre-ordered the Universal Monster Collection, The Hitchcock Collection, Harvey and Lawrence of Arabia, all on blu-ray, for less money than what Amazon US wants just for the Hitchcock Collection. The Indiana Jones set was about the same price, but for some reason the Univeral UK releases are cheaper, much cheaper, than the american releases. And they are region free.